As Shown in the Figure, a 1 $v _ { 1 }$

Multiple Choice

As shown in the figure, a 1.45-kg block is held in place against the spring by a 21-N horizontal external force. The external force is removed, and the block is projected with a velocity $v _ { 1 }$ =1.2 m/s as it separates from the spring. The block descends a ramp and has a velocity $v _ { 2 } = 2.1 \mathrm {~m} / \mathrm { s }$ at the bottom. The track is frictionless between points A and B . The block enters a rough section at B , extending to E. The coefficient of kinetic friction between the block and the rough surface is 0.29 . The velocity of the block is $v _ { 3 } = 1.4 \mathrm {~m} / \mathrm { s }$ at C. The block moves on to D, where it stops. How much work is done by friction between points B and C ?

A) -7.0 J
B) -1.8 J
C) -14 J
D) -6.4 J
E) -3.6 J